1. Field of the Invention
The present invention relates to a method of installing a valve seat in a valve body and, more particularly, to a method of installing an annular valve seat having a radially outwardly opening, annular channel into a valve body having a radially inwardly projecting, annular rib such that the annular rib is received in the channel.
2. Description of the Background
In a conventional butterfly valve, the valve seat against which the disk seals is made of an elastomeric material, such as rubber, and is disposed in a valve body which generally encircles the valve seat. A typical example of such a butterfly valve is shown in U.S. Pat. No. 2,994,342 in which the valve has a body with a radially inwardly extending, annular, dove-tail rib, and an elastomeric seat having an annular web with two radially outwardly extending annular flanges, the web and flanges defining a radially outwardly opening channel, complementary in shape to that of the rib. Accordingly, when the seat is received in the valve body, there is interlocking between the valve body and the elastomeric seat, the annular web serving also as a reinforcement or backup to the relatively soft resilient seat.
In U.S. Pat. No. 4,685,611 there is shown an improved butterfly valve assembly in which the seat includes a rigid reinforcing member which is bonded to and generally embedded in the seat but which, like the seat described above, forms an annular, radially outwardly opening channel which, when emplaced in the valve body, receives the annular rib. Seats made in accordance with U.S. Pat. No. 4,685,611, while still retaining sufficient flexibility to be inserted into a valve body having an annular rib as described above, are nonetheless more rigid than an unreinforced seat, such as is shown in U.S. Pat. No. 2,994,342. This is particularly true in smaller valve sizes, e.g. 4" and less, where even the unreinforced valve seats exhibit considerable rigidity.
Heretofore, in installing the reinforced valve seats, particularly in the smaller sizes mentioned above, in field operations, e.g. to replace a worn out seat, it required considerable manual effort to install the valve seats in the valve body. primarily because of the fact that it is difficult to manually, radially collapse the valve seat sufficiently to allow the reinforced valve seat to be placed in the valve body and have the channel receive the rib.